Perry and Williams met up first, spending much of the evening chatting and laughing on the back patio over two rounds of drinks.
They were joined later by Van Veen and then Mayer, who arrived under a large brimmed hat and greeted Perry with a kiss. The two singers held hands at the table and continued the PDA when they left around 11:15 p.m., standing hand-in-hand in the lobby before heading out.
“They actually buried the hatchet a while back, and they are friends,” a Perry source told PEOPLE recently.
These days, the source added, Perry “is focused on her career and making herself happy.”